#ifndef __PROCESS_POOL_HPP_
#define __PROCESS_POOL_HPP_

#include<iostream>
#include<cstdlib>
#include<vector>
#include<unistd.h>
#include<sys/wait.h>
#include"Task.hpp"

//先描述

class Channel
{
public:
    Channel(int fd, pid_t id) : _wfd(fd), _subid(id)
    {
        _name = "channel-" + std::to_string(_wfd) + "-" + std::to_string(_subid);
    }    

    ~Channel(){}

    void Send(int code)
    {
        int n = write(_wfd, &code, sizeof(code));
        (void)n;
    }

    void Close()
    {
        close(_wfd);
    }

    void Wait()
    {
        pid_t rid = waitpid(_subid, nullptr, 0);
        (void)rid;
    }

    int Fd() {return _wfd;};
    pid_t SubId(){return _subid;};
    std::string Name(){return _name;};

private:
    int _wfd;
    pid_t _subid;
    std::string _name;
};

//再组织

class ChannelManager
{
public:
    ChannelManager() : _next(0){}
    
    void Insert(int wfd, pid_t subid)
    {
        _channels.emplace_back(wfd, subid);
    }

    Channel &Select()
    {
        auto &c = _channels[_next];
        _next++;
        _next %= _channels.size();
        return c;
    }

    void PrintChannel()
    {
        for(auto &channel : _channels)
        {
            std::cout << channel.Name() << std::endl;
        }
    }

    void StopSubProcess()
    {
        for(auto &channel : _channels)
        {
            channel.Close();
            std::cout << "关闭" << channel.Name() << std::endl;
        }
    }

    void WaitSubProcess()
    {
        for(auto &channel : _channels)
        {
            channel.Wait();
            std::cout << "回收" << channel.Name() << std::endl;
        }
    }

    ~ChannelManager(){}

private:
    std::vector<Channel> _channels;
    int _next;
};

const int gdefaultnum = 5;

class ProcessPool
{
public: 
    ProcessPool(int num) : _process_num(num)
    {
        _tm.Register(PrintLog);
        _tm.Register(Download);
        _tm.Register(Upload);
    }

    void Work(int rfd)
    {
        while(true)
        {
            int code = 0;
            ssize_t n = read(rfd, &code, sizeof(code));
            if(n > 0)
            {
                if(n != sizeof(code))
                {
                    continue;
                }
                std::cout << "子进程[" <<getpid() << "]收到一个任务码:" <<
                code << std::endl;
                _tm.Execute(code);
            }
            else if(n == 0)
            {
                std::cout << "子进程退出" << std::endl;
                break;
            }
            else{
                std::cout << "读取错误" << std::endl;
                break;
            }
        }
    }

    bool Start()
    {
        for(int i = 0; i < _process_num; i++)
        {
            //创建管道
            int pipefd[2] = {0};
            int n = pipe(pipefd);
            if(n < 0) 
                return false;
            //创建子进程
            pid_t subid = fork();
            if(subid < 0) return false;
            else if(subid == 0)
            {
                //子进程
                //关闭不需要的文件描述符
                close(pipefd[1]);
                Work(pipefd[0]);
                close(pipefd[0]);
                exit(0);
            }
            else{
                //父进程
                //关闭不需要的文件描述符
                close(pipefd[0]);//写端
                _cm.Insert(pipefd[1], subid);
            }
        }
        return true;
    }

    void Debug()
    {
        _cm.PrintChannel();
    }

    void Run()
    {
        //1、选择一个任务
        int taskcode = _tm.Code();

        //2、选择一个信道，负载均衡的选择子进程完成任务
        auto &c = _cm.Select();
        std::cout << "选择了一个子进程：" << c.Name() << std::endl;
        c.Send(taskcode);
        std::cout << "发送了一个任务码: " << taskcode << std::endl;
    }

    void Stop()
    {
        _cm.StopSubProcess();
        _cm.WaitSubProcess();
    }

    ~ProcessPool()
    {}

private:
    ChannelManager _cm;
    int _process_num;
    TaskManager _tm;
};

#endif